Fig. 4
From: Muscarinic acetylcholine receptor signaling generates OFF selectivity in a simple visual circuit
mAchR-B mediates light-induced inhibition of glu-OLP. a Schematic diagram illustrating the insertion of a Gal4-DBD element into the 5′-UTR region of the mAchR-B gene. Orange bar: coding exons. Light blue bar: introns. b The mAchR-B enhancer line reveals broad expression of the receptor in the third instar larval brain. Representative projected confocal images with EGFP expression driven by the mAchR-B enhancer (green) and anti-VGluT staining (gray) are shown. Blue arrow: glu-lOLP. c mAchR-B expresses in glu-lOLP but not cha-lOLP. The mAchR-B enhancer-driven EGFP signal colocalizes with the VGluT-positive glu-lOLP (blue arrow), but not with the ChAT-positive cha-lOLP (pink arrow). Representative projected confocal images are shown. Scale bars are as indicated. d, e Expression of mAchR-BRNAi dampens cha-lOLP’s ON response and eliminates both glu-lOLP’s ON and OFF responses. The dashed green and gray lines indicate the 100 ms light or dark pulse, respectively. The genotypes are as indicated. The d average traces of the changes in lOLP > RCaMP signals and e quantification of peak values of changed intensity (ΔF/F) are shown. Shaded areas on traces and error bars on quantifications represent SEM. Control, n = 8; mAchR-BKK107137, n = 6. cha-lOLP, ON: p = 0.0388, t = 2.320, df = 12; cha-lOLP, OFF: p = 0.3201, t = 1.037, df = 12; glu-lOLP, ON: p < 0.0001, t = 10.09, df = 12; glu-lOLP, OFF: p = 0.0028, t = 3.736, df = 12. Statistical significance was determined by Student’s t test. p ≥ 0.05 was considered not significant, ***p < 0.001, **p < 0.01, and *p < 0.05
